Levels of peat in compost declined in recent years due to pressure from green groups, but mainly due to a peat shortage.

Ireland harvests four million cubic metres of peat per year, the majority of which is burnt in power stations.

But the wet summer of 2012 meant that just 1.5 million cubic metres was dug up. Supplies recovered last year though, with six million cubic metres harvested.

Gardening expert Peter Seabrook said: “Testing the pH of multi-purpose compost bought by researchers across the UK, of the same brand, they gave readings from pH5 (acid) to pH8 (very alkaline).

“Gardeners have no chance of getting satisfactory results when composts like this are so variable from bag-to-bag

“Indications are that peat percentages in potting composts are set to rise in the coming season. It will become easier to find 100 per cent peat or high peat compost.”

Friends of the Earth’s policy director, Craig Bennett, hit out at the return of peat bales.

Craig said: “The government has stated that it wants peat gone from garden centres by 2020. The industry promised it would get behind this commitment. By launching a 100 per cent peat-based product, Bord na Mona stuck two not-so-green fingers up to the government.”